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TAS6422-Q1: Over current issue

Part Number: TAS6422-Q1

Hi Team,

I would like to get some help for the situation of our customer below:

The customer used TAS6422-Q1 in their end product powered by 14.4V (battery voltage) with two 2 Ohm loudspeakers.

The problem was, on the full volume the second loudspeaker goes into overcurrent fault and disables itself.

It is always channel 2 and not channel1. They play mono sound files, so the sound level should be the same for both speakers.
If only plug in a loudspeaker to channel 1 everything works fine even on full volume.

Do you have any idea what might cause this? Or how to debug this?
Also according to the datasheet, the amplifier should run a diagnosis on the faulty channel and if it does not detect an error it should enable again? But according to their test the channel just goes to HI-Z. Should the software reenable the channel itself?

Let me know if you need more information.

Thanks!

Jonathan

  • Jonathan,

    May you dump all the register when this problem happens. I need to find the root cause of OC reported.

    Dylan

  • Hello Dylan,

    Jonathan put my support request here, so i will answer here:

    The strange thing is, that the overcurrent error only happesn if both laudspeakers are connected. If only one speaker is connected on either channel 1 or channel 2, it does not happen.

    If you need any more info, please tell me and i will try to acquire it.

    The requested register dump in the error state:

    [0x0]: 0x0
    [0x1]: 0x32
    [0x2]: 0x62
    [0x3]: 0x4
    [0x4]: 0x0
    [0x5]: 0xff
    [0x6]: 0xff
    [0x7]: 0xcf
    [0x8]: 0xcf
    [0x9]: 0x0
    [0xa]: 0x0
    [0xb]: 0x11
    [0xc]: 0x0
    [0xd]: 0x0
    [0xe]: 0x0
    [0xf]: 0x15
    [0x10]: 0x40
    [0x11]: 0x0
    [0x12]: 0xc
    [0x13]: 0x1c
    [0x14]: 0x0
    [0x15]: 0x0
    [0x16]: 0x0
    [0x17]: 0x0
    [0x18]: 0x0
    [0x19]: 0x0
    [0x1a]: 0x0
    [0x1b]: 0x0
    [0x1c]: 0x0
    [0x1d]: 0x0
    [0x1e]: 0x0
    [0x1f]: 0x0
    [0x20]: 0x0
    [0x21]: 0x88
    [0x22]: 0x1
    [0x23]: 0x14
    [0x24]: 0x3
    [0x25]: 0x0
    [0x26]: 0x40
    [0x27]: 0x60
    [0x28]: 0xa

  • Hi Dominik,

    From the registers value, CH2 has OC fault. And from 0x12 and 0x13 registers, CH1 and CH2 also were overtemperature.

    Can you add one fun on heat-sink to reduce the temperature firstly?

    We should make sure there is no OT fault firstly.

    Regards,

    Derek 

  • Hello Derek.

    Yes, we saw the overtemperture error too.

    We tried to improve the heatsinking but the error still occoured. I will try to get a register dump with the improved heatsinking, but that will take a bit time, as it only really happens in the car.

    The strange thing is this only happens if two loudspeakers are connected and it is always channel 2. Also i cant really reproduce it on my bench and in the car it happens always after a few seconds on full volume.

  • Hi Dominik,

    Can you swap the CH1 and CH2 inductors and test again?

    I am afraid that the rate current of inductors will be reduced on high temperature case.

    Regards,

    Derek

  • Hi Derek,

    The CH1 and CH2 inductors are the same type on this board ( FDSD0420-H-3R3M=P3, selected according to sloa242a.pdf). So i am not sure on how i would swap them.

    If temperature might be a problem for them, desoldering the CH2 inductors and swapping them with the CH1 inductors will not change their temperature based on location. And i cant really swap the traces going to them. The board is pretty thight at this location.

    But i will try to add extra heatsinking to the inductors and try again, and then report back.

    kind regards

    Dominik

  • Hi Dominik,

    Please make sure there is no OT fault firstly. I am afraid that OT lead to OC fault.

    Regards,

    Derek

  • Hi Derek,

    i will try again to get a hold of the car with the module with improved cooling, so i can get the register dumps.But now before christmas everyone is very busy :-)

    In the mean time i found a temporary fix: If i reduce the gain setting to 7.6V peak, both loudspeakers work (but it is ofcourse not as loud).

    kind regards

    Dominik

  • Hi Dominik,

    Reduce the gain, it will also reduce the output power with same input signal level. 

    And the heat also will reduce with output power.

    Regards,

    Derek